RU2136791C1 - TEXTILE FIBERS FROM SULFATED POLY-p-PHENYLENE- TEREPHTHALIAMIDE - Google Patents

Abstract

FIELD: synthetic fibers. SUBSTANCE: invention provides cloth that can be rapidly dyed to deep shades and is composed of poly-p-phenylene-terephthaliamide with intrinsic viscosity (IV) value from 1.5 to 4.0 determined from equation: IV = ln(η_rel)/c, wherein c is concentration of polymer in solution (0.5 g of polymer in 100 ml of 96% sulfuric acid) and η_rel ratio of polymer and solvent consumptions measured at 30 C in capillary viscosimeter, and characterized by modulus less than 200 g/denier and rupture elongation above 6%. Distinguishing feature of product is that it contains 5 to 20 mol sulfur in the form of sulfonate groups per 100 mol polymer links and has, in polymer structure, Charaguchi crystals determined by X-ray diffraction at angle 2θ and characterized by primary peak with angle approximately 23 deg. and two smaller angles 17 and 27 deg. determined over width of equatorial angular diffraction. EFFECT: accelerated and simplified dyeing process under atmosphere conditions involving small amounts of dye with no carrier. 3 cl, 1 tbl, 4 ex

Description

 The invention relates to fibers of textile quality from sulfonated poly (p-phenylene terephthalamide). The fibers of the present invention can be quickly dyed to deep shades without using a carrier. They are characterized by light tortuosity and other desirable qualities.

 US patents NN 4075269 and 4162346, issued February 21, 1978 and July 24, 1979 to Jones and others describe the spinning of sulfonated poly (p-phenylene terephthalamide) with a low characteristic viscosity of the fiber. Jones et al. Indicate that sulfonated polyamide can be prepared from a suitable sulfonated diamine or derivatives of dibasic acids or mixtures thereof. Alternatively, poly (p-phenylene terephthalamide) (PPD-T) can be sulfonated by the method of Jones et al. Using either concentrated sulfuric acid or fuming sulfuric acid. Freshly formed fibers prepared in accordance with the patents of Jones et al. Are characterized by tensile strength per yarn of about 10 grams per denier, elongation of about 2.5% and an initial modulus of about 200 grams per denier. Jones et al. Subjected the freshly formed fiber to heat treatment to achieve a value of at least 15 grams denier, elongation of at least 1.5%, for example 2-3.5%, and a modulus of at least 400 grams denier. Such fibers have high characteristics, but not for the production of high-quality textile products.

 The present invention provides the production of fibers from sulfonated poly (p-phenylene terephthalamide) with a characteristic viscosity of from about 1.5 to 4 and from 5 to 20 mol of sulfur content in the form of sulfo groups per 100 mol of polymer units, and said fiber has a modulus of less than 200 grams per denier and lengthening more than 6%.

 Fibers made from PPD-T are well known for their exceptionally high strength and high modulus. For some types of practical application, for example, for textiles, a high modulus is a drawback, since the fabrics made from this material are very stiff and create inconvenience to use. In addition, the stainability and especially the ease of dyeing, which implies the ability to quickly dye to deep shades without the use of a carrier or high-pressure equipment, becomes an important factor in the manufacture of clothing, which is a difference from industrial use. It is often believed that the use of paint carriers is undesirable from an environmental point of view. It was found that fibers prepared from sulfonated PPD-T have an intrinsic viscosity of about 1.5 to 4 and contain 5 to 20 mol of sulfur in sulfo groups per 100 mol of p-phenylene terephthalamide units (repeating units in the polymer chain), which makes their properties necessary for creating comfort, and fabrics from such textiles are easily dyed.

 By PPD-T is meant a homopolymer formed during the polymerization of p-phenylenediamine and terephthaloyl chloride, and also homopolymers formed as a result of the incorporation of small amounts of other diamines with p-phenylenediamine and / or small amounts of other chlorides of dibasic acids with terephthaloyl chloride. In general, other diamines and other dibasic acid chlorides can be used in amounts up to about 10 mol% of p-phenylenediamine or terephthaloyl chloride, provided that the other diamines and dibasic chlorides do not contain reactive groups that interfere with the polymerization reaction. The preparation of PPD-T is described in US patents NN 3869429, 4308374 and 4698414.

 In the practice of the present invention, in order to achieve a high intrinsic viscosity (greater than about 5), PPD-T is mixed with sulfuric acid at a concentration of 100.2-102% to obtain the desired degree of sulfonation of the PPD-T molecules. The conditions are carefully regulated so that PPD-T is destroyed, i.e. its molecular weight is reduced to provide a characteristic viscosity (Jν) of about 1.5 to 4 (calculated by yarn), and at the same time, the desired degree of sulfonation.

 The degree of sulfonation and the degree of destruction or degradation are in equilibrium, which is regulated by the concentration of sulfuric acid, the concentration of the polymer in the solution, the time of exposure of the polymer to the acid, and the temperature of the solution upon exposure.

 It was found that it is useful to use sulfuric acid with a concentration of from 100.2 to 102% in solution. Concentrations of acid in excess of 105% can cause unwanted abrupt polymer breakdown. The choice of polymer concentration is an important point in obtaining the products according to the invention. The concentration of the polymer over 15 weight. % in the solution will not produce the expected crystal structure, the polymer will not undergo effective destruction, i.e., when the value of Jν exceeds 4.

The time and temperature at which the polymer is in contact with the acid also affect the degree of sulfonation and degradation of the polymer. Temperatures in the range from 75 to 120 ^o C and the time from 10 minutes to 2 hours were useful.

 The intrinsic viscosity value, which was determined as described below, is a measure of the molecular weight of the polymer and serves as an indicator of the stiffness of fracture or degradation when the polymer is subjected to a sulfonation process.

When preparing the fibers according to the invention, it is convenient to prepare the spinning solution by dissolving PPD-T at the desired concentration in fuming sulfuric acid. The concentration of the polymer in the acid is usually about 9 to 15 weight. % and preferably about 12 wt.%. The concentration level should not exceed 15 weight. % to guarantee the presence of a crystal of Haraguchi form in the final fiber. The crystal of the Kharaguchi form is characterized by a single main peak of diffraction at a Bragg angle of approximately 25 ^° and two smaller peaks, for one of them the Bragg angle is approximately 17 ^° and the other approximately 27 ^° , determined by the width of the equatorial angular diffraction. The presence of a Haraguchi crystal is a characteristic feature of the fibers of the present invention.

 The sulfonation conditions in the present invention lead to sulfur levels of 5 to 20 mol (based on the content of sulfo groups per 100 mol of polymer units). The determination of sulfur content is described below.

 The fibers of the present invention can be spun under spinning conditions with an air gap in accordance with US Pat. No. 3,767,756 or in wet spinning conditions as described by Kwolek (US 3,671,542). If desired, the fibers of this invention can be obtained in color by adding pigment to the spinning solution. Sulphonated PPD-T solution can be extruded through spinnerets, the hole size of which is in the range from about 0.025 to 0.25 mm in diameter. The number, size, shape and configuration of the holes of the die can vary in order to achieve the desired fibrous product. The extruded paste of the spinning dope of the polymer is fed into the coagulation bath with or without its preliminary passage through a non-coagulating fluid layer, which is usually used as air, but any other inert gas or liquid that is a non-coagulant for the paste can be used. The thickness of the non-coagulating layer of the medium is usually from 0.1 to 10 cm.

The coagulation bath is water and may contain up to 70% sulfuric acid. Preferred temperatures are temperatures in the range of from about 25 to 80 ^° C. or slightly higher.

 After extruding the paste through a coagulation bath, the paste is coagulated into a swollen acid / water fiber, the fiber must be thoroughly washed in the first acid extract and then the acid groups must be neutralized. The fiber washing solution may be water and then alkaline water. Wet and swollen fiber is then sent to the stage of drying the fiber with low tension or without tension, due to the quality of the final fiber product. Drying the fibers under tension typically causes a decrease in elongation at break and an increase in modulus and tensile strength.

 Sulfonated PPD-T fibers of the present invention are easily dyed. In particular, they can be deeply stained as described below without the use of a carrier and without high pressure, which means that they will release paint from a dye bath that does not contain a carrier or additional chemicals that are added to swell the fibers. They are suitable for producing fire-resistant fabrics due to their lack of thermal shrinkage. The achieved high moisture absorption and good absorbency contribute to the convenience in the manufacture of fabrics from this fiber.

Testing Methods
The intrinsic viscosity (Jν) is determined by the equation
Jν = ln (η _rel ) / c,
where c is the concentration (0.5 g of polymer in 100 ml of solvent) of the polymer solution and η _rel (relative viscosity) is the ratio between the flow rate of the polymer solution and the solvent, determined at 30 ^o C on a capillary viscometer, the values of the characteristic viscosity were determined, as reported using concentrated sulfuric acid (96% H ₂ SO ₄ ).

 The module is considered as the slope of the initial stress / force curve (load, tension). The module is first calculated in g / unit denier, which is then converted to dN / tex units. Each dimension is the average of 5 breaks.

 Elongation is the percentage of increase in length at break.

 Sulfur content.

A small amount of yarn sample (about 0.5 g) is dissolved in about 96% sulfuric acid, and then water is added to precipitate the polymer. Water is then continuously added to thoroughly wash the polymer to remove any free sulfate, such as sodium sulfate, from the polymer. The resulting polymer sample is then dried and carefully weighed before being placed in a Schoniger flask for burning in pure oxygen. SO ₂ and SO ₃ generated by combustion are absorbed by water to form sulfuric acid. The acid is titrated using barium chloride to determine the sulfur content as bound to sulfonic acid or as sulfo groups, or an initial sample of yarn.

Stain test
About 4 g of a fiber sample is dried to constant weight at 60 ^o C. In a 500 ml beaker, a paint solution is prepared containing 4% of each component, calculated on the basis of the weight of Basacryl Red Gl fiber (Basic Red 29) (types of dye) and sulfate sodium in 400 ml of water. The dye solution is heated with stirring under vigorous boiling under atmospheric pressure. A fiber sample was added and stirring and boiling was continued for up to 45 minutes. During this time, the beaker covers itself freely to avoid minimal water loss. After a certain time, the fiber mass is removed, squeezed to dryness from the dye solution, and dried to constant weight at 60 ^° C. The test can be modified by changing the dye content in the bath, the temperature of the bath, and the exposure time in the bath. An increase in any of these indicators is expected to enhance the color of the duck.

 Then the fiber is wrapped around the carding tape and its color is determined (on a Hunter colorimeter in daylight). The spent dye solution is diluted with water to 400 ml to compensate for any losses during boiling and its color is determined by fixing the absorption value "L" at 492 nm in 0.1 mm cell. At L = 0, the color is black, and at L = 100 it is white. Tintability is evaluated either by the loss of paint from the dye solution, which is proportional to the decrease in the color of the solution, or by the increase in the color of the fiber. Both indicators are sensitive to dispersion. The trained eye easily classifies the relative stainability of the samples without colorimetric determination.

 The following examples illustrate the invention, but should not be construed as limiting.

 Example 1. This example illustrates the preparation of sulfonated poly (p-phenylene terephthalamide) having properties similar to textiles, which can be quickly dyed to deep shades in the absence of a carrier.

In a continuous process, dry poly (p-phenylene terephthalamide) (PPD-T) with an intrinsic viscosity of 6.3 dl / g (dl is the deciliter, deciliter / g is the true intrinsic viscosity unit) was mixed with 100.4% sulfuric acid in jacketed high-speed mixer for preparing a spinning solution with 12.0% by weight of PPD-T in H ₂ SO ₄ . The temperature of the solution was maintained at about 110 ^° C. The solution was pumped through a transport line at a jacket temperature of 80 ^° C to a tank-tank at a temperature of jacket of 70 ^° C. The total residence time of the solution for spinning in the mixer and transport line was about 30 minutes. The holding time in the collection tank was approximately 1.5 to 2 hours with thorough mixing to achieve uniformity and homogeneity of the polymer concentration. A sample of the spinning solution was taken at the inlet of the collector, and the characteristic viscosity of the polymer was 2.7 dl / g. This indicates that the polymer was destroyed and sulfonated as it passed from the mixer through the conveyor line.

The spinning solution was turned into filament yarn by conventional wet spinning. The solution was continuously taken from the collector and pumped through a conveyor line at a jacket temperature of 70 ^° C into two spinning heads, each of which consisted of a metering pump and a spunbond unit. The temperature in all parts of the spinning heads was maintained at 70 ^° C. Then, the solution was squeezed out of dies, which were immersed to a depth of about 7.6 cm in aqueous coagulation liquid. The aqueous coagulation liquid contained approximately 10% sulfuric acid and its temperature was maintained at 80 ^° C. Each of the dies had 3715 openings with a diameter of 0.035 mm. The extruded filaments passed through the coagulation fluid at a small angle of inclination at a distance of about 53.3 cm before exiting the coagulation bath. The coagulated filaments were collected as a tow, washed with water, neutralized with a 0.4% NaOH solution at 40 ^° C. and washed again with water. The fully washed and neutralized tow was then dried and wound onto a bobbin at a speed of 50 yards / min (45.7 m / min). The moisture content of the dried yarn was approximately 12% based on the weight of the polymer at the end of the drying.

The intrinsic viscosity of the resulting yarn was approximately 2.40 dl / g. This amounts to 11,145 denier (approximately 10,000 dtex) with 1.5 denier per thread. The tensile strength was 5.0 g / denier, the elongation at break was 9.3%, and the initial modulus was 140 g / denier. The density was about 1.44 g / cm ³ and the humidity was about 8.5%. This fiber contained 15 mol of sulfur in the form of sulfonate groups per 100 mol of polymer units of p-phenylene terephthalamide in the polymer.

X-ray diffraction of the width of the equatorial angle of this fiber was characterized by the presence of a single-peak profile (crystal of the Kharaguchi form) at a Bragg angle (two theta) of about 23 ^o instead of the two-peak profile, which is typical for high-strength PPD-T fiber with a high modulus. It is widely known from the literature that the two-peak profile (a Northolt-shaped crystal) consists of a diffraction peak at a Bragg angle of 21 ^° and another peak at 23 ^° (for reference see "Aromatic High-Strength Fibers" by HHYang, Wiley-interscience, New York, 1989, pp. 253-259).

 The above fiber has a unique dyeability. Under atmospheric conditions, the fiber released a bath dye for 10 minutes and was dyed deep red.

 Example 2. This example illustrates the preparation of the dyed fiber of the invention.

The procedure of Example 1 was repeated except that a 5 wt.% Solution of green pigment from pharmaceutical sage in sulfuric acid was added at about 60 ^° C. to the dope solution to the dope head. The flow rate and concentration of the non-pigmented dope and the pigment solution were controlled so that the final pigmented dope solution contained about 12% of the total solid components by weight of the polymer.

 The pigmented solution was spun in a manner similar to example 1 with the formation of strands of green sage.

 Example 3. This example illustrates another preparation of sulfonated poly (p-phenylene terephthalamide) with textile-like properties, which can be quickly dyed to a deep color in the absence of a carrier.

 The fiber was prepared in a manner analogous to Example 1 except that sulfuric acid was used at a concentration of 101.0%. The intrinsic viscosity of the yarn for the dope fiber was 2.99 dl / g. The tensile strength (gpd) / elongation (%) / modulus (gpd) of the fiber was 2.8 / 8.1 / 90.0. The fiber density was 1.43, and the fiber contained 18 mol of sulfur in the form of sulfonate groups per 100 mol of p-phenylene terephthalamide. The second sample, which was taken from the same spinning and yarn for the spinning fiber, gave a value of 3.05 dl / g with a ratio of tensile strength, elongation and modulus of 3.7 / 8.3 / 120. The density of this fiber was 1.43, and it contained 16 mol of sulfur in the form of sulfonate groups per 100 mol of polymer units of p-phenylene terephthalamide in the polymer. The diffraction profiles of these samples according to the values of the width of the equatorial angles during x-ray diffraction analysis were the same as in example 1, and these fibers were characterized by unique dyeability when they were dyed under atmospheric conditions, and the fibers released a bath dye for ten minutes and were dyed deep red .

 Example 4. This example illustrates the improvement in the dyeability of the fibers of the present invention compared to that in the prior art. The fibers described in Euro Patent Application No. 427280, under the name Chiou, were prepared according to the procedure of this application and dyed as described in Example 1.

 As can be seen from the table, the fibers obtained according to the prior art, it is difficult to dye to deep shades, this requires a carrier, a long time, an increased concentration of the dye or an increased temperature of the bath in order to achieve deep and dark shades. In contrast, the fibers of this invention are capable of dyeing to very deep shades very quickly under normal atmospheric conditions using small amounts of dye and without carrier.

Claims (3)

1. A fiber of textile quality, which quickly dyes to deep shades, consisting of poly (p-phenylene terephthalamide) with a value of intrinsic viscosity (Jν) determined by the equation
Jν = ln (η _rel ) / c,
where c is the concentration (0.5 g of the polymer in 100 ml of 96% sulfuric acid) of the polymer in solution;
η _rel is the ratio of the flow rate of the polymer solution and the solvent,
measured at 30 ^o C in a capillary viscometer, 1.5 to 4.0, characterized by a modulus of less than 200 g / denier and an elongation at break of more than 6%, characterized in that it contains from 5 to 20 moles of sulfur in the form of sulfonate groups per 100 moles of polymer units, which enable the fiber to dye to deep shades, and has Kharaguchi crystals in the polymer structure, determined by x-ray diffraction at an angle of 2θ and characterized by a main peak with an angle of about 23 ^o , and two smaller ones with angles of 17 and 27 ^o , determined by equatorial width th diffraction angle.  2. The fiber according to claim 1, characterized in that it further comprises a pigment. 3. A method of producing textile-grade fiber, comprising mixing poly (p-phenylene terephthalamide) having an intrinsic viscosity of greater than about 5, measured at 30 ^° C. at a concentration of 0.5 g of polymer in 100 ml of concentrated sulfuric acid, with a sulfuric acid concentration of from 100 , 2 to 102% at elevated temperature, molding the solution in an aqueous coagulation bath to form fibers, removing them from the bath and neutralizing, characterized in that they use about 9, but not more than 15 wt.% Poly (p-phenylene terephthalamide), and mixing osuschest lyayut at 95 - 120 ^o C for from about 10 minutes to about 120 minutes, as long as the polymer will contain from 5 to 20 mols of sulfur as sulfonate groups per 100 moles of repeating polymer units, and does not degrade to a value of intrinsic viscosity less than 4, measured at 30 ^o C at a concentration of 0.5 g of polymer in 100 ml of concentrated sulfuric acid, and the fiber after neutralization has a modulus of less than 200 g / denier, elongation of more than 6%, can be dyed to deep colors and is characterized by in the polymer structure of Hara crystals gucci determined by x-ray diffraction at an angle of 2θ and characterized by a main peak with an angle of about 23 ^o , and two smaller ones with angles of 17 and 27 ^o , determined by the width of the equatorial angular diffraction.

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